1. Field of the Invention
The present invention relates to an improved form, fill, seal and separate packaging machine of the type primarily intended for use in packaging material in reclosable containers. The packaging machine of this invention is uniquely characterized by its means for applying zipper material to the web and subsequently forming, filling and separating a plurality of easily openable and reclosable containers.
2. Description of the Prior Art
One of the most significant advancements in the field of flexible packaging in recent years has been the introduction of reclosable, zipper-type plastic bags. While such containers have been publicly available for a number of years for general household use, only recently have such packages been introduced at a retail level for the sale of prepackaged items such as, for example, food products.
As the desirability of such reclosable packages for retail sales has been recognized, so has the need for efficient equipment for automatically forming, filling and sealing such reclosable containers. Numerous such devices are available today, but virtually all such machines presently available share inherent deficiencies primarily related to handling the zipper-type lock strip in the manufacturing and filling process. The packaging industry clearly recognizes that such zipper-type reclosable locks must be substantially impermeable, particularly when the containers are filled with food products, and unnecessary stressing of the reclosable seals must be avoided during the forming and filling process. Accordingly, many present devices for forming, filling, sealing and separating reclosable containers orient the container vertically with the zipper-lock along one vertical edge during the filling process. One example of such a device is disclosed in U.S. Pat. No. 4,745,731 to Talbott, et al. According to the disclosure of that patent, the reclosable container is formed by wrapping the plastic web around a generally vertical fill tube, mating the opposed parts of the zipper-type lock to form a tube, and then filling the receptacles from an open end. Nevertheless, substantial manipulation of the web is required, and great care must be taken to mate the corresponding closure parts to insure a properly formed and sealed container.
It has also been noted in the industry that it would be desirable to construct a machine for forming reclosable containers wherein the zipper-lock material is added to the container base web during the container-forming operation. U. S. Pat. No. 4,812,074 discloses an apparatus for accomplishing this result. However, the apparatus of that patent is limited by its disclosure of the use of zipper material wherein the mating halves are joined one to the other by a unitary zipper web. This requires great precision in applying the zipper, and further requires that the material be folded precisely once the zipper material has been applied to the base web so that the reclosable feature will function properly. Furthermore, opening such a container requires severing the relatively thick and strong zipper web that extends between its mating halves.
It is, therefore, clear that there remains a great need in the art for a form, fill, seal and separate packaging machine suitable for packaging material in reclosable containers wherein the web and particularly its reclosable zipper-type lock are easily bonded to each other and are relatively unaffected and not subjected to mechanical stress during the forming, filling, sealing and separating procedures. Furthermore, such a device should be capable of relatively simple adjustment to accommodate the manufacture of reclosable packages of various sizes and weight content. Finally, such a device should, preferably, include means for easily opening the finished, sealed container while maintaining the container's integrity until it is initially opened.